Fatal snakebite-induced thrombotic microangiopathy with incidental rheumatic heart disease: an autopsy case report

Thrombotic microangiopathy (TMA) is an uncommon but serious complication of hemotoxic snakebite envenomation, which remains a significant cause of morbidity and mortality in tropical regions. TMA is characterized by microvascular thrombosis and hemolytic injury, which may lead to multiorgan dysfunction. We report the case of a 31-year-old male factory worker with an alleged viper bite to the right great toe. Despite administration of multiple doses of anti-snake venom and intensive supportive care, his condition progressively deteriorated, and he succumbed. Medicolegal autopsy revealed a hemorrhagic lesion at the bite site, diffuse subdural and subarachnoid hemorrhages, and petechial hemorrhages over the heart. Toxicological analysis of preserved skin tissue from the bite site confirmed the presence of hematotoxic venom. Histopathological examination of the kidneys showed renal cortical necrosis with thrombosis of the afferent arterioles and glomerular capillary loops, along with red blood cell extravasation, consistent with thrombotic microangiopathy secondary to envenomation. An incidental finding of fibrotic thickening of the mitral and aortic valves with myxoid degeneration and the presence of Anitschkow cells was consistent with rheumatic valvular disease. This case highlights the importance of autopsy, toxicological confirmation, and histopathological examination in establishing a diagnosis of venom-induced thrombotic microangiopathy and identifying occult cardiac pathology with potential medicolegal relevance.